In a twin-belt casting machine the moulding cavity is formed by means of moving walls, the lower wall being formed by the upper run of a lower endless flexible belt, the upper wall being formed by the lower run of an upper endless flexible belt, and the side walls being formed by a pair of spaced endless side dams, that move with the belts along the opposite sides of the moulding cavity from the inlet (or entrance) to the outlet (or exit) thereof and that are guided by guide means during their movement along the moulding cavity. The lower wall and the upper wall are cooled by contact with a cooling liquid on their respective reverse surfaces. That is, the cooling liquid is applied to the lower surface of the upper run of the lower belt, and the cooling liquid is also applied to the upper surface of the lower run of the upper belt.
Molten metal is fed in at the entrance of the moulding cavity, and a cast product is delivered at the outlet of the moulding cavity. Thus, the side dams pass during their movement along the moulding cavity successively through a first zone, in which they face molten metal and through a second zone located downstream from the first zone in which they face solidified metal.
Such a process and apparatus are described in U.S. Pat. No. 3,036,348. In this known process and apparatus, there is a fixed guide in the form of a guide bar extending for a substantial distance along the outer face of each side dam. This guide bar extends from the inlet towards the outlet of the moulding cavity and, during their movement along the moulding cavity, the side dams are only cooled by the contact of their upper and lower faces with the belts. As shown in FIG. 10 of that U.S. patent and as described in column 10, lines 60-70 therein, it is known in the twin-belt casting machine art to provide a longitudinal passageway in each stationary dam which rests on top of the respective moving side dam adjacent to the pool of molten metal near the entrance to the moulding cavity and to feed liquid coolant through such passageways for cooling the stationary side dams. It is also known in the twin-belt casting machine art to provide a longitudinal passageway in each guide bar and to feed liquid coolant through such a passageway for cooling the guide bar.
However, such guide bars and such stationary edge dams are stationary. Prior to the present invention, the moving side dams have only been cooled by the contact of their upper and lower surfaces with the belts. Relatively insignificant cooling is provided from such a stationary side dam or from such a stationary guide bar. Consequently, in the known process and apparatus relatively few calories are carried off from the moving side dams as they move along opposite sides of the moulding cavity. Thus, the moving side dams become heated to a relatively high temperature during their movement along the moulding cavity. Such repeated high temperature heating influences in an unfavorable way the lifetime of these side dams. This high temperature heating of the side dams also imposes limitations on the casting speed, especially when rather thick products are cast, for example, products with a thickness of five or more centimeters.